Everything is possible because its capitalization has reached a very high level. And at the end of 2018, it is possible that it can reach 40 000$.
No doubt the capitalization has reached a very high value and that determines the market status of the coin and that it is the top coin in the market right now, it still might not be able to cross the $40000 value in the end of the year for sure.
The rise in the value is not determined by the market capitalization but by the market forces and the market is very slow so it will take Bitcoin some time to regain its last years values first. If things went favorable, the market value might cross $30000 or even $40000 in 2019 or 2020.